1. Field
A separator and a rechargeable lithium battery is disclosed.
2. Description of the Related Technology
A conventional non-aqueous rechargeable lithium battery typically includes a separator made of a porous insulating film and interposed between positive and negative electrodes, and the pores of the film typically are impregnated by an electrolyte solution including a lithium salt dissolved therein.
The non-aqueous rechargeable lithium battery has excellent high-capacity and high energy density characteristics. However, when the positive and negative electrodes of the non-aqueous rechargeable lithium battery are repetitively contracted and expanded during the repeated charge and discharge cycles they may react with a separator or an electrolyte, and thus, the non-aqueous rechargeable lithium battery may be easily deteriorated, have internal and external short circuits, and rapidly become hot.
The separator may be fused and rapidly contracted or destroyed and thus, short-circuited when the temperature of the battery rapidly increases. In order to prevent this problem, a conventional separator is typically formed of a porous polyethylene film to prevent shutdown. The shutdown typically indicates that a separator is partly fused and thus, closes pores and cuts off a current, when a battery is heated up due to overcharge, external or internal short circuit. In addition, an attempt has been made to improve safety of the non-aqueous rechargeable lithium battery by improving heat resistance of a separator and in particular, to secure safety even when a separator therein is sharply contracted or destroyed.